linux-kernel - [PATCH 3.2 08/46] x86, sparse: Do not force removal of __user when calling copy_to/from_user

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Date:	Sun, 12 Jun 2016 22:34:41 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Peter Zijlstra" <peterz@...radead.org>,
	"Thomas Gleixner" <tglx@...utronix.de>, mingo@...hat.com,
	"Steven Rostedt" <rostedt@...dmis.org>, h.zuidam@...puter.org,
	"Andi Kleen" <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	"Jaccon Bastiaansen" <jaccon.bastiaansen@...il.com>
Subject: [PATCH 3.2 08/46] x86, sparse: Do not force removal of __user
 when calling copy_to/from_user_nocheck()

3.2.81-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Steven Rostedt <rostedt@...dmis.org>

commit df90ca969035d3f6c95044e272f75bf417b14245 upstream.

Commit ff47ab4ff3cdd "x86: Add 1/2/4/8 byte optimization to 64bit
__copy_{from,to}_user_inatomic" added a "_nocheck" call in between
the copy_to/from_user() and copy_user_generic(). As both the
normal and nocheck versions of theses calls use the proper __user
annotation, a typecast to remove it should not be added.
This causes sparse to spin out the following warnings:

arch/x86/include/asm/uaccess_64.h:207:47: warning: incorrect type in argument 2 (different address spaces)
arch/x86/include/asm/uaccess_64.h:207:47:    expected void const [noderef] <asn:1>*src
arch/x86/include/asm/uaccess_64.h:207:47:    got void const *<noident>
arch/x86/include/asm/uaccess_64.h:207:47: warning: incorrect type in argument 2 (different address spaces)
arch/x86/include/asm/uaccess_64.h:207:47:    expected void const [noderef] <asn:1>*src
arch/x86/include/asm/uaccess_64.h:207:47:    got void const *<noident>
arch/x86/include/asm/uaccess_64.h:207:47: warning: incorrect type in argument 2 (different address spaces)
arch/x86/include/asm/uaccess_64.h:207:47:    expected void const [noderef] <asn:1>*src
arch/x86/include/asm/uaccess_64.h:207:47:    got void const *<noident>
arch/x86/include/asm/uaccess_64.h:207:47: warning: incorrect type in argument 2 (different address spaces)
arch/x86/include/asm/uaccess_64.h:207:47:    expected void const [noderef] <asn:1>*src
arch/x86/include/asm/uaccess_64.h:207:47:    got void const *<noident>

Cc: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/r/20140103164500.5f6478f5@gandalf.local.home
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Jaccon Bastiaansen <jaccon.bastiaansen@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: mingo@...hat.com
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: h.zuidam@...puter.org
---
 arch/x86/include/asm/uaccess_64.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -233,13 +233,13 @@ __must_check unsigned long __clear_user(
 static __must_check __always_inline int
 __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size)
 {
-	return __copy_from_user_nocheck(dst, (__force const void *)src, size);
+	return __copy_from_user_nocheck(dst, src, size);
 }
 
 static __must_check __always_inline int
 __copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
 {
-	return __copy_to_user_nocheck((__force void *)dst, src, size);
+	return __copy_to_user_nocheck(dst, src, size);
 }
 
 extern long __copy_user_nocache(void *dst, const void __user *src,